Project Summary A lack of information, along with targeted advertising, addition of palatable flavors, and misconceptions about their safety has led to a dramatic increase in the use of electronic nicotine delivery systems (e-cigarettes), with sales of e-cigarettes rising from $20 million in 2008 to $1.5 billion in 2014. In adolescents, continuing annual increases in e-cigarette use have been particularly high and e-cigarette use has now surpassed that of traditional cigarettes within this population. The neurobiology of the adolescent brain produces a behavioral phenotype that increases reward-seeking behavior and makes them engage in more impulsive and risky behaviors, including experimental drug use. These findings warrant a critical need for more research on the effects of nicotine vapor exposure on adolescent health, including its effects on the malleable adolescent brain and the behavior that it controls. We posit that adolescent exposure to nicotine vapor results in long-term dramatic changes in reward seeking behaviors. Based on the results of a limited number of studies investigating the effects of nicotine on decision making and cue-induced motivation for rewards, we predicted that repeated exposure to nicotine vapor will cause a significant and persist increases in impulsive choice, decreases in risky choice, and decreases in cue-induced potentiation of reward seeking behavior, in both male and female rats. Additionally, we expect that specific nicotinic receptor subtypes, particularly within the striatum, will predict reward choice and motivation. We will test these predictions using cost-benefit decision making and Pavlovian- to-instrumental transfer tests with food pellets as the reward. The goal of this research is to determine if exposure to nicotine vapor during adolescence causes significant long-term changes in impulsive or risky choice (Aim 1a) or long-term changes in the ability of reward paired cues to invigorate reward seeking behavior (Aim 1b). Additionally, relationships between reward motivation or reward choice and nicotinic ?4?2 receptor levels in the brains of rats, with and without a history or adolescent nicotine vapor exposure, will be determined (Aim 2). This research will provide immediate and much needed information about this rising and potentially devastating addictive trend, commonly observed in adolescents.